Size Matters: The Impact of Avatar Size on User Experience in Healthcare Applications

TL;DR

The paper examines how avatar size affects user experience in a wall-projected healthcare application by testing five MetaHuman avatars integrated with an AI chatbot. Using a within-subjects design with 23 participants, it assesses usability, trust, and social presence via UEQ+, Trust, and Social Presence measures. Results show avatar size impacts attractiveness and perspicuity, with medium sizes rated best, while social presence is more strongly tied to stimulation and attractiveness than to size. The study highlights gender differences in avatar size preferences and discusses implications for avatar design and proxemics in virtual healthcare environments.

Abstract

The usage of virtual avatars in healthcare applications has become widely popular; however, certain critical aspects, such as social distancing and avatar size, remain insufficiently explored. This research investigates user experience and preferences when interacting with a healthcare application utilizing virtual avatars displayed in different sizes. For our study, we had 23 participants interacting with five different avatars (a human-size avatar followed by four smaller avatars in a randomized order) varying in size, projected on a wall in front of them. The avatars were fully integrated with an artificial intelligence chatbot to make them conversational. Users were asked to rate the usability of the system after interacting with each avatar and complete a survey regarding trust and an additional questionnaire on social presence. The results of this study show that avatar size significantly influences the perceived attractiveness and perspicuity, with the medium-sized avatars receiving the highest ratings. Social presence correlated strongly with stimulation and attractiveness, suggesting that an avatar's visual appeal and interactivity influenced user engagement more than its physical size. Additionally, we observed a tendency for gender-specific differences on some of the UEQ+ scales, with male participants tending to prefer human-sized representations, while female participants slightly favored smaller avatars. These findings highlight the importance of avatar design and representation in optimizing user experience and trust in virtual healthcare environments.

Figures (4)

• Figure 1: Experimental setup where users interacted with 5 different avatars from 0 to 4 respectively decreasing in size. (Image 0 = Human-size avatar: Scale magnitude in Unreal engine: 1 (roughly 175cm in height when projected on the wall), image 1 = Scale magnitude: 0.85 ( 150cm), image 2 = Scale magnitude: 0.7 ( 130cm), image 3 = Scale magnitude: 0.55 ( 100cm), image 4 = Smallest avatar: Scale magnitude: 0.4 ( 70cm).
• Figure 2: Average UEQ ratings for the avatar sizes (0 = Human-size avatar, 4 = Smallest avatar) on the dimensions of Attractiveness and Perspicuity, with error bars representing the standard error of the mean (SEM).
• Figure 3: Radar chart depicting average UEQ+ ratings of the female participants for the different avatar sizes (0 = Human-size avatar, 4 = Smallest avatar).
• Figure 4: Radar chart depicting average UEQ+ ratings of the male participants for the different avatar sizes (0 = Human-size avatar, 4 = Smallest avatar).